Research Of The Multi-functional Logic Devices Based On Surface Plasmon Polaritons

With the development of modern information science and technology,the research of artificial neural networks has been further in-depth.It has solved many problems that modern computers can not deal with in the fields of system identification and control,economy,biology and medicine,showing its powerful function and potential.However,the traditional artificial neural network model has low computational efficiency and high energy consumption,so how to break through the limitations of traditional electronic technology to the artificial neural network is particularly important.Combined with the features of integrated optical technology,such as fast computing speed and low loss,optical neural network system promotes the development of photonic integrated technology and neural network in artificial intelligence,intelligent perception and intelligent cognition with its ultra-high computing speed,high computing precision and ultra-low power consumption.As the core of the optical neural network system,the basic optical logic device supporting optical neural network is an important factor to determine the successful landing of optical neural network system.Early optical logic devices were based on semiconductor lasers and optical amplifiers.Although these devices could achieve corresponding logic functions,their performance in optical computing applications was not satisfactory due to their size and power consumption.In subsequent studies,due to the limitation of the diffraction limit,the size of silicon-based devices needs to be larger than half wavelength range,which cannot meet the requirements of highly integrated photonic devices.With the further study of Surface Plasmon Polaritons(SPPs),the manipulation of light in the subwavelength range is realized on the basis of breaking through the conventional diffraction limit of light,and the integration of optical logic devices is further improved.Based on surface plasmons,two multi-functional logic devices with different operation modes and logic functions are designed in this dissertation.Specific research contents are as follows:1.The Drude theory model is used to define the characteristics of the metals in the simulation,and the theoretical research is carried out on the physical characteristics such as the excitation and propagation of the surface plasmons.The coupling mode theory is used to carry out the numerical analysis on the coupling process of the metal-insulator-Metal(MIM)foundation model of the logic devices.The numerical simulation of the proposed model was carried out by using Finite-difference Time-domain(FDTD)method.2.A logic device that can realize multiple logic functions at the same time is proposed.It consists of a Mach-Zehnder Interferometer(MZI)waveguide and a pair of identical hexagonal resonators embedded with rotatable ellipses.The proposed structure is simulated by the finite difference Time domain method.Finally,four logical functions can be implemented simultaneously: NOR,AND,OR,and NOT.By calculating the simulation results,the contrast results of the four logic gates are obtained.Compared with similar logic devices,the proposed logic devices have better performance.Therefore,the structure has a good application prospect in the field of optical communication and photonic-integrated equipment.3.A logic device is proposed which can realize all the basic logic functions.It is composed of two hexagonal resonators with rectangular inlaid and three MIM waveguides.By inputting a specific phase of light into the upper and lower waveguides,all the logic functions can be realized at the same wavelength by using the mutual interference of the two beams of light.The performance of its logic function at this wavelength is calculated and analyzed by simulation.The logic device can play the role of a generalist in the optical integrated circuit,without changing the device when the logic function of the device needs to be changed,which further improves the integration of the optical integrated device.